title: On the mechanism of water oxidation by a bimetallic manganese catalyst: a density functional study.
abstract: Density functional theory is used to explore possible mechanisms that lead to water oxidation by a bimetallic manganese catalyst developed by McKenzie and co-workers. On the basis of our calculations we propose that the key active intermediate is a mixed valent Mn(III)(μ-O)Mn(IV)-O˙ oxyl radical species, the oxyl centre being the site of nucleophilic attack by water. The mixed-valent species is in equilibrium with an isomeric diamond-core Mn(IV)(μ-O)(2)Mn(IV) structure, which acts as reservoir for the active species. The chemistry appears to be unique to pentadentate ligands because these shift the position of the equilibrium between the Mn(III)(μ-O)Mn(IV)-O˙ and Mn(IV)(μ-O)(2)Mn(IV) isomers, such that significant concentrations of the former are present in solution.
authors.affiliation: Inorganic Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford, United Kingdom OX1 3QR.
authors.forename: W M C
authors.initials: WM
authors.lastname: Sameera
authors.forename: Christine J
authors.initials: CJ
authors.lastname: McKenzie
authors.forename: John E
authors.initials: JE
authors.lastname: McGrady
mesh_terms: D002384:Catalysis; D019075:Electrophoresis, Capillary; D008345:Manganese / Q000737:chemistry*; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000737:chemistry*; D010084:Oxidation-Reduction; D021241:Spectrometry, Mass, Electrospray Ionization; D013056:Spectrophotometry, Ultraviolet; D014867:Water / Q000737:chemistry*
chemical_list: D009942:Organometallic Compounds; D014867:Water; D008345:Manganese